Levoit Desktop True HEPA 3-Stage Replacement Filter captures at least 99.97% of airborne particles 0.3 microns in size, so you can enjoy fresh air even longer. Enhance your workspace with the Levoit Desktop Aromatherapy True HEPA Air Purifier. With 3-stage filtration, the purifier freshens your space and infuses it with essential oils so that working is a breeze. To do its best work, Levoit recommends replacing the filter every 6-8 months - the filter may need to be replaced sooner or later depending on the air quality in your area. Includes 2 replacement filters.